Semiconductor device having a group-III nitride superlattice layer on a silicon substrate

Abstract

Provided is a semiconductor device containing a silicon single crystal substrate 101 , a silicon carbide layer 102 provided on a surface of the substrate, a Group III nitride semiconductor junction layer 103 provided in contact with the silicon carbide layer, and a superlattice-structured layer 104 constituted by Group III nitride semiconductors on the Group III nitride semiconductor junction layer. In this semiconductor device, the silicon carbide layer is a layer of a cubic system whose lattice constant exceeds 0.436 nm and is not more than 0.460 nm and which has a nonstoichiometric composition containing silicon abundantly in terms of composition, and the Group III nitride semiconductor junction layer has a composition of Al x Ga Y In z N 1-α M α (0≦X, Y, Z≦1, X+Y+Z=1, 0≦α<1, M is a Group V element except nitrogen).

1. A semiconductor device comprising a silicon single crystal substrate, a silicon carbide layer provided on a surface of the substrate, a Group III nitride semiconductor junction layer provided in contact with the silicon carbide layer, and a superlattice-structured layer constituted by Group III nitride semiconductors on the Group III nitride semiconductor junction layer, wherein the silicon carbide layer is a layer of a cubic system whose lattice constant exceeds 0.436 nm and is not more than 0.460 nm and which has a nonstoichiometric composition containing silicon abundantly in terms of composition, and the Group III nitride semiconductor junction layer has a composition of Al x Ga Y In z N 1-α M α  (0≦X, Y, Z≦1, X+Y+Z=1, 0≦α<1, M is a Group V element except nitrogen). 
     
     
       2. The semiconductor device according to  claim 1 , wherein the superlattice-structured layer constituted by Group III nitride semiconductors is a layer formed by alternately stacking aluminum gallium nitride (Al x Ga 1-x N: 0≦X≦1) layers having different aluminum (Al) composition ratios. 
     
     
       3. The semiconductor device according to  claim 2 , wherein a layer having a low Al composition ratio among the aluminum-gallium nitride layers having different aluminum composition ratios is in contact with the Group III nitride semiconductor junction layer. 
     
     
       4. The semiconductor device according to  claim 1 , wherein the superlattice-structured layer constituted by Group III nitride semiconductors is a layer formed by alternately stacking gallium indium nitride (Ga Q In 1-Q N: 0≦Q≦1) layers having different gallium (Ga) composition ratios. 
     
     
       5. The semiconductor device according to  claim 4 , wherein a layer having a high gallium (Ga) composition ratio among the gallium indium nitride layers having different gallium (Ga) composition ratios is in contact with the Group III nitride semiconductor junction layer. 
     
     
       6. The semiconductor device according to  claim 1 , wherein the superlattice-structured layer constituted by Group III nitride semiconductors has a film thickness in the range from 5 monolayers (MLs) to 30 MLs. 
     
     
       7. The semiconductor device according to  claim 1 , wherein the silicon single crystal substrate is a substrate whose surface is a (111) crystal plane, and the Group III nitride semiconductor junction layer is a hexagonal wurtzite crystal type aluminum nitride (AlN) layer. 
     
     
       8. The semiconductor device according to  claim 1 , wherein the silicon single crystal substrate is a substrate whose surface is a (001) crystal plane, and the Group III nitride semiconductor junction layer is a cubic zinc blende crystal type aluminum nitride (AlN) layer.